A construction machine such as an excavator has been used to perform work at civil engineering work site for performing excavation of earth and sand or gravel.
In general, as important components, such an excavator includes a lower driving structure, an upper swing structure mounted to swing on the lower driving structure, and a cab for an operator fixedly arranged on the upper swing structure.
As illustrated in FIG. 1, a cab in the related art is constructed to include a bottom frame, front poles positioned in front to extend upward from the bottom frame, and rear poles positioned in the rear.
In general, various kinds of construction equipment having different sizes have been produced even if such equipment may be of the same type, but one kind of cab structure is typically applied to such various kinds of construction equipment.
Since the cab structure must endure the heavy load of the equipment, cross sections of cab strength members are increased to cause the field of front vision to be narrowed and cab manufacturing cost to be increased.